A quick-thinking plumber aided by surgeon and TV talk show host Dr. Mehmet Oz gave critical first aid to a British tourist who was hit by an out-of-control taxicab Tuesday morning near a busy midtown Manhattan corner, according to witnesses at the scene.

The unidentified woman was eating a hot dog with a friend just after 11 a.m. near 1251 Avenue of the Americas when she was struck by the taxicab, officials said. The woman was pinned against the cab after it slammed into a wall surrounding a fountain in front of the building, officials said. Her right leg was severed below the knee, officials said.

Plumber David Justino rushed over to the scene and used his belt as a tourniquet until paramedics arrived.

Oz, who was in the Avenue of the Americas building, heard the commotion and soon was on the street checking the tourniquet and providing assistance, according to his spokesman Tim Sullivan.

"It was really the work of the paramedics and the Good Samaritan plumber who dealt with this," Sullivan said.

The woman was taken to Bellevue Hospital Center in critical but stable condition. She underwent surgery to have the leg reattached, but it was not known if the procedure was successful, the NYPD said.

The taxi driver, identified by the Taxi and Limousine Commission as Mohammad F. Himon, 24, first struck a bicyclist as the biker turned west on West 49th Street from Sixth Avenue before hitting the woman, police said.

The bicyclist had minor injuries that were treated at the scene, officials said.

Himon was given a summons for violating commission code by being an unauthorized driver of the taxi at the time of the accident. A police spokesman said the investigation is continuing.